A photogravure printing press includes plurality of cells defined by printing-direction walls and substantially perpendicular walls formed in each of image areas on the circumferential surface of a gravure roll. A plurality of substantially perpendicular cuts are formed in each of the substantially perpendicular walls. In the central portion of the image area, each of the substantially perpendicular cuts is formed so as to have a gap greater than the width of each of the printing-direction walls and the substantially perpendicular walls.
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1. A photogravure press, with which paste films are formed on a substrate sheet by gravure printing, the photogravure press comprising:
a gravure roll having image areas on a circumferential surface thereof and having print paste applied thereon so as to form the paste films; and
an impression cylinder facing the gravure roll having the substrate sheet sandwiched therebetween; wherein
a printing direction corresponds to a direction in which the gravure roll and impression cylinder rotate;
in each image area, printing-direction walls extending in substantially the printing direction and perpendicular walls extending substantially perpendicularly to the printing-direction walls are disposed, and a plurality of cells are defined by the printing-direction walls and the perpendicular walls; and
in order for the adjacent cells to communicate with each other, each of the perpendicular walls has substantially perpendicular cuts formed therein.
2. The photogravure press according to
3. The photogravure press according to
4. The photogravure press according to
5. The photogravure press according to
6. The photogravure press according to
7. The photogravure press according to
8. The photogravure press according to
9. The photogravure press according to
10. The photogravure press according to
11. The photogravure press according to
12. The photogravure press according to
13. The photogravure press according to
14. The photogravure press according to
15. A method for manufacturing a multilayer-ceramic electronic component comprising:
providing the photogravure press according to
printing the paste films with the photogravure press.
16. The method for manufacturing a multilayer-ceramic electronic component according to
17. The method for manufacturing a multilayer-ceramic electronic component according to
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1. Field of the Invention
The present invention relates to a photogravure press used for manufacturing a multilayer-ceramic electronic component and a method for manufacturing a multilayer-ceramic electronic component, conducted by using the photogravure press, and in particular, the present invention relates to a technique for improving smoothness of a paste film formed by gravure printing.
2. Description of the Related Art
In order to manufacture a multilayer-ceramic electronic component such as a multilayer ceramic capacitor, for example, a step of forming a conductive paste film functioning as an internal electrode on a ceramic green sheet is executed. The internal electrode defined by the conductive paste film is required to have high patterning accuracy. As a technique for satisfying the above requirement, gravure printing has attracted attention (for example, see Japanese Unexamined Patent Application Publication No. 9-76459 (hereinafter, referred to as Patent Document 1)).
Patent Document 1 discloses an apparatus for manufacturing an electronic component, in which, in order to make uniform the thickness of the peripheral portion of the paste film formed by gravure printing, of a plurality of cells formed in each of image areas which have print paste applied thereon and which are formed on the circumference surface of a gravure roll, a portion of the cells lying in the peripheral portion of the image area are formed so as to have open areas that are smaller than those of another portion of the cells lying in the central portion of the image area, and the depths of the cells lying in the peripheral portion are made smaller than those of the cells lying in the central portion.
Unfortunately, in the apparatus disclosed in Patent Document 1, since the cells formed in the image area are independent from each other, the ratio of the area of the cells with respect to the overall area of the image area is relatively small, and also, since print paste between the adjacent cells is unlikely to flow during printing, the apparatus is not suitable for forming a paste film especially having a relatively large area and often causes unevenness of printing.
As a technique for solving the above-described problems, for example, Japanese Examined Utility Model Registration Application Publication No. 5-41015 (hereinafter, referred to as Patent Document 2) has proposed a photogravure plate, although not intended to be applied to electronic components, in which walls defining a plurality of cells in an image area are arranged so as to extend at an angle with the printing direction and have cuts so as to allow the adjacent cells to communicate with each other.
According to the technique set forth in Patent Document 2, the ratio of the area of a region (that is, the cells and the cuts) in which the print paste can be held can be increased with respect to the overall area of the image area, and also, it can be expected that the print paste flows through the cuts.
Unfortunately, according to the technique set forth in Patent Document 2, since the gap of each cut is formed smaller than the width of each wall, when print paste, such as conductive paste, having a relatively high viscosity is used, the print paste is limited to flow between the adjacent cells, thereby sometimes causing a printed paste film to have a trace of the cell or forming a rough paste film.
Also, according to the technique set forth in Patent Document 2, since the walls defining the plurality of cells formed in the image area are arranged so as to extend at an angle with the printing direction, so-called stringiness of the print paste occurs at an angle with the circumferential surface of the gravure roll when a substrate sheet is detached from the gravure roll, whereby local irregularities are likely to occur in the peripheral portion of the printed paste film. Inconstancy in the direction of the stringiness causes reciprocal overlapping, which leads further to variation in the thickness of paste films.
In order to overcome the problems described above, preferred embodiments of the present invention provide a photogravure press used for manufacturing a multilayer-ceramic electronic component and a method for manufacturing a multilayer-ceramic electronic component performed by using the photogravure press.
The present invention is first directed to a photogravure press used for manufacturing a multilayer-ceramic electronic component, with which paste films to be patterned layers defining part of a laminate to be provided in the multilayer-ceramic electronic component are formed on a substrate sheet by gravure printing.
The photogravure press includes a gravure roll having image areas formed on the circumferential surface thereof and having print paste applied thereon so as to provide the paste films, and an impression cylinder facing the gravure roll having the substrate sheet sandwiched therebetween. In each image area, a plurality of printing-direction walls extending in the printing direction and a plurality of substantially perpendicular walls extending substantially perpendicularly to the printing-direction walls are disposed, and a plurality of cells defined by the printing-direction walls and the substantially perpendicular walls is formed.
In order to solve the foregoing problems, the photogravure press having the above structure is constructed as follows.
That is, in order for the adjacent cells to lie in communication with each other, each of the substantially perpendicular walls has a plurality of substantially perpendicular cuts formed therein so that the substantially perpendicular wall extends intermittently, having the substantially perpendicular cuts interposed therein. In addition, in the central portion of the image area, each of the substantially perpendicular cuts is formed so as to have a gap greater than the width of each of the printing-direction walls and the substantially perpendicular walls. With this structure, even when print paste having a relatively high viscosity is used, the print paste can flow smoothly between the adjacent cells, thereby resulting in a uniform thickness of each paste film formed by gravure printing.
In a first modification of the photogravure press according to preferred embodiments of the present invention, a portion of the plurality cells lying in the peripheral portion of the image area are formed so as to have smaller open areas than those of another portion of the plurality of cells lying in the central portion of the image area. With the above-described structure of the photogravure press of a preferred embodiment of the present invention, a so-called “saddle phenomenon” is prevented from occurring. The “saddle phenomenon”, meaning that the paste film is a peripheral portion thicker than its central portion, is generally likely to occur when gravure printing is applied for forming a paste film. In the event a multilayer ceramic electronic component is manufactured by using a conductive paste film having such a “saddle phenomenon” occurred therein, sometimes a short circuit or a structural defect occurs.
In the first modification, each of the printing-direction walls extends continuously in the image area, two kinds of the substantially perpendicular walls are alternately disposed in the printing direction such that one lies in contact with any one of the printing-direction walls and the other lies in contact with the above printing-direction wall, having the corresponding substantially perpendicular cut interposed therebetween, and each cell has the substantially perpendicular cuts at its two corners diagonally opposed to each other. With this structure, local irregularities are prevented from occurring in the peripheral portion of each paste film formed by gravure printing, and the smoothness of the paste film is further improved.
In the first modification, at least one start-edge groove extending substantially perpendicularly to the printing direction is preferably disposed on the printing-start side of the image area so as to be independent of the cells. With this structure, slight touching or deficiency in thickness of the corresponding paste film is prevented from occurring on its printing-start side.
Also, in the first modification, it is preferable that the outermost ones of the printing-direction walls have no substantially perpendicular cuts formed outside thereof.
In a second modification of the photogravure press according to preferred embodiments of the present invention, each of the printing-direction walls has a plurality of printing-direction cuts formed therein so that the substantially perpendicular wall extends intermittently, having the printing-direction cuts interposed therein. Also, the printing-direction walls are disposed so as to intersect with the substantially perpendicular cuts, the substantially perpendicular walls are disposed so as to intersect with the printing-direction cuts, and either one of the substantially perpendicular cuts and the printing-direction cuts is disposed at each corner of each of the cells.
In the second modification, a portion of the cells lying on the printing-start side and another portion lying on the printing-end side of the image area are preferably formed so as to have the same open area as each other.
In the photogravure press according to preferred embodiments of the present invention, it is preferable that the image area have an outline groove formed therein, having a constant width and defining at least a portion of the outline thereof. With this structure, the linearity of the peripheral outline of the corresponding paste film formed by gravure printing can be improved.
Also, all of the plurality of cells are preferably substantially identical in depth. With this structure, since the thickness of the corresponding paste film formed by gravure printing is affected by the open areas of the cells, the thickness of the paste film can be easily controlled by the open areas of the cells.
In addition, the length of the image area extending in the circumferential direction of the gravure roll is preferably formed smaller than a nip width provided by the gravure roll and the impression cylinder. With this structure, since the entire image area can be in contact with a substrate sheet in the printing step, print paste can be uniformly transferred onto the substrate sheet, whereby slight touching due to an insufficient transfer amount of the print paste is unlikely to occur in the substrate sheet.
The present invention is also directed to a method for manufacturing a multilayer-ceramic electronic component, conducted by using the photogravure press of the preferred embodiments of the present invention described above. With the above application of the photogravure press, the characteristics of the obtained multilayer-ceramic electronic components can be stabilized, the occurrence of defective products can be reliably prevented, and the manufacturing yield can be greatly improved.
In the method for manufacturing a multilayer-ceramic electronic component according to the present invention, gravure printing is preferably used for forming conductive paste films to define internal electrodes. That is, it is preferable that conductive paste be used so as to serve as the print paste, and that the paste film formed by the print paste be a conductive paste film to define an internal electrode. With this arrangement, the thickness of the conductive paste films can be made uniform, thereby preventing a short circuit and faulty insulation from occurring in the obtained multilayer-ceramic electronic component.
In the above case, the substrate sheet is preferably a ceramic green sheet.
Other features, elements, characteristics, steps and advantages of the present invention will become more apparent form the following detailed description of preferred embodiments with reference to the attached drawings.
The photogravure press 1 includes a gravure roll 2 and an impression cylinder 4 facing the gravure roll 2, having a substrate sheet 3 sandwiched therebetween. The gravure roll 2 and the impression cylinder 4 rotate respectively in the directions of arrows 5 and 6 so as to transport the substrate sheet 3 in the direction of an arrow 7.
The photogravure press 1 is used for manufacturing a multilayer-ceramic electronic component such as a multilayer-ceramic capacitor. More particularly, the photogravure press 1 is used for forming paste films on the substrate sheet 3 by gravure printing, to be patterned layers defining part of a laminate to be provided in the multilayer-ceramic electronic component. To be more specific, as shown in
As shown in
As shown in
The image areas 13 have patterns corresponding to those of the conductive paste films 9 shown in
The image area 13 has a plurality of printing-direction walls 15 extending in the printing direction and a plurality of substantially perpendicular walls 16 extending in a direction that is substantially perpendicular to the printing-direction walls 15 and thus has a plurality of cells 17 formed therein, defined by the printing-direction walls 15 and the substantially perpendicular walls.
When respective open areas of the plurality of cells 17 are viewed, cells 17(A) lying in the peripheral portion of the image area 13 are formed so as to have smaller open areas than those of cells 17(B) lying in the central portion of the image area 13. In order to make the open areas of the cells 17(A) lying in the peripheral portion smaller, each of the printing-direction walls 15 and the substantially perpendicular walls 16 lying in the peripheral portion of the image area 13 is formed so as to have a greater width than that of those lying in the other portion. With this structure, the “saddle phenomenon” described in the Description of the Related Art is prevented from occurring.
Also, in order for the adjacent cells 17 to lie in communication with each other, each of the substantially perpendicular walls 16 has a plurality of substantially perpendicular cuts 18 formed therein so that the substantially perpendicular wall extends intermittently, having the substantially perpendicular cuts 18 interposed therein.
In addition, each of the printing-direction walls 15 extends continuously in the image area 13. Two kinds of the substantially perpendicular walls 16 are alternately disposed in the printing direction such that one lies in contact with any one of the printing-direction walls 15, and the other lies in contact with the above printing-direction wall 15, having the corresponding substantially perpendicular cut 18 interposed therebetween. As a result, each cell 17 has the substantially perpendicular cuts 18 at its two corners diagonally opposed to each other.
With the foregoing structure, the conductive paste 12 (see
On the contrary, as a comparative example, when the printing-direction walls 15 are formed so as to extend intermittently, and the substantially perpendicular walls 16 are formed so as to extend continuously, it has been confirmed that the conductive paste film 9 has relatively large irregularities in thickness.
With this structure, even when the conductive paste 12 having an example viscosity of about 0.1 Pa·s to about 40 Pa·s higher than that of general gravure ink is used, a constant flow is smoothly generated in the printing direction, thereby reliably providing a uniform thickness in each of the conductive paste films 9. Although the printing-direction walls 15 and the substantially perpendicular walls 16 preferably have the same width W as each other in the present preferred embodiment shown in the figure, the walls 15 and 16 may have different widths from each other.
Referring again to
The image area 13 also has an outline groove 21 formed therein, defining at least a portion of the outline thereof and having a constant width. Meanwhile, the outline groove 21 may have different widths in the printing direction and the perpendicular direction from each other. In the present preferred embodiment, the outline groove 21 has a constant depth and is formed along three sides of the image area 13 other than a side on the printing-start side of the same. With this structure, linearity of the outline of the conductive paste film 9 can be improved.
Each of outermost printing-direction walls 15(A) of the printing-direction walls 15 has no substantially perpendicular cuts 18 formed outside thereof. Such a structure contributes to improving the foregoing linearity of the edges of the conductive paste film 9, especially its edges extending in the printing direction.
Although, as described above, the cells 17(A) lying in the peripheral portion are formed so as to have smaller open areas than those of the cells 17(B) lying in the central portion with respect to the respective open areas of the cells 17, all of the cells 17 are formed so as to be substantially identical in depth regardless of the sizes of their open areas. Accordingly, the thickness of the conductive paste film 9 is affected by the open areas of the cells 17, whereby the thickness of the conductive paste film 9 can be easily controlled.
The gravure roll 2 and the impression cylinder 4 have the substrate sheet 3 (see
In the present preferred embodiment, the length L of the image area 13 extending in the circumferential direction of the gravure roll 2 is smaller than the nip width N. With this arrangement, since the entire image area 13 comes into contact with the substrate sheet 3, and then the substrate sheet 3 is detached from the gravure roll 2 during printing, the conductive paste 12 does not flow rearwards from the print end of the image area 13, thereby uniformly transferring the conductive paste 12 onto the substrate sheet 3, as a result, advantageously preventing slight touching due to an insufficient transfer amount of the conductive paste 12 from occurring in the conductive paste film 9.
Especially, in the case where the printing-direction walls 15 extend continuously in the corresponding image area 13 as in the present preferred embodiment, the conductive paste 12 flows in the printing direction only in the regions surrounded by the printing-direction walls 15, thereby effectively preventing occurrence of irregularities on the surface of the conductive paste film 9.
When the conductive paste film 9 is formed by the photogravure press 1 having the above-described structure, its entire surface can be made smooth and excellent linearity of its peripheral outline can be achieved.
When the ceramic green sheet 8 having the conductive paste films 9 as shown in
In such a multilayer-ceramic electronic component, since the entire conductive paste film 9 is smoothly formed as described above, a stress is not locally concentrated in the crimping step, thereby preventing a short circuit through a ceramic layer caused by mutual contact of the internal electrodes and faulty insulation due to a local small thickness of the ceramic layer.
In each of the preferred embodiments shown in
In the preferred embodiment shown in
Furthermore, each one of the first to the fourth preferred embodiments as described above, has a common feature in that the perpendicular cuts 18, which are adjacent to each other in the printing direction, take different positions from each other in the perpendicular direction with respect to the printing direction.
The foregoing structure effectively prevents a partial thinning of the conductive paste 12 (see
Also, the stringiness of the conductive paste 12 which occurs when the ceramic green sheet 8 is detached from the gravure roll 2, proceeds continuously through the perpendicular cuts 18. Therefore, an above-described misalignment of the positions of the perpendicular cuts 18 which are adjacent to each other, in the perpendicular direction with respect to the printing direction, effectively prevents occurrence of irregularities on the surface of the conductive paste film 9 which may be caused by the stringiness of the conductive paste 12.
The preferred embodiment shown in
The preferred embodiment shown in
The cells 17(A) lying in the peripheral portion of the image area 13 are formed so as to have smaller open areas than those of the cells 17(B) lying in the central portion of the image area 13. With this structure, the “saddle phenomenon” is unlikely to occur.
Also, as well illustrated in
In addition, the image area 13 has the outline groove 21 disposed therein, having a constant width and defining at least a part of its outline. Meanwhile, the outline groove 21 may have different widths in the printing direction and the substantially perpendicular direction from each other. Also, the outline groove 21 is formed along the circumference of the image area 13 in the present preferred embodiment. The presence of such an outline groove 21 improves linearity of the edges of the conductive paste film 9.
Furthermore, all of the plurality of cells 17 are preferably substantially identical in depth. Thus, the thickness of the conductive paste film 9 is easily controlled by the open areas of all the cells 17.
Still furthermore, preferably the present preferred embodiment has a structure as described by referring to
Moreover, in the preferred embodiment shown in
Although the present invention has been described in connection with the preferred embodiments illustrated in the figures, a variety of modifications are possible within the scope of the present invention.
For example, although the image area 13 preferably has a substantially rectangular shape in the preferred embodiments illustrated in the figures, the shape of the image area can be arbitrarily changed in accordance with a pattern of the conductive paste film 9 to be formed by gravure printing.
Also, although the substrate sheet 3 is formed by the ceramic green sheet 8 lined with the carrier film 10, and the conductive paste films 9 are formed on the ceramic green sheet 8 in the preferred embodiments illustrated in the figures, for example, the substrate sheet 3 may be formed only by a resin sheet such as the carrier film 10, and the conductive paste films 9 may be formed on the resin sheet. In this case, the conductive paste films 9 formed on the resin sheet are transferred onto the ceramic green sheet 8 in the subsequent step.
In addition, the paste films formed by gravure printing are the conductive paste films 9 in the preferred embodiments illustrated in the figures, they may be films composed of, for example, paste-like ceramic slurry. To be more specific, for example, in a multilayer-ceramic capacitor, in order to absorb steps generated by the thickness of internal electrodes, step-absorbing ceramic layers are sometimes formed in regions of the capacitor having no steps formed therein, and the present invention is applicable to forming paste films composed of the ceramic slurry so as to provide such ceramic layers.
The present invention is not limited to each of the above-described preferred embodiments, and various modifications are possible within the range described in the claims. An embodiment obtained by appropriately combining technical features disclosed in each of the different preferred embodiments is included in the technical scope of the present invention.
Hashimoto, Akira, Tabata, Kazuhiro, Takashima, Hiroyoshi, Kanayama, Yoshihiro, Nishizawa, Takahiro
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Jul 09 2004 | HASHIMOTO, AKIRA | MURATA MANUFACTURING CO LTD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 014844 | /0963 | |
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Jul 09 2004 | NISHIZAWA, TAKAHIRO | MURATA MANUFACTURING CO LTD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 014844 | /0963 |
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